The present invention generally relates to fabrication of semiconductor devices and more particularly to a fabrication process of a semiconductor device including a dicing process of a semiconductor wafer and an apparatus therefor.
In a fabrication process of semiconductor devices, a very large number of semiconductor devices are formed commonly on a single semiconductor wafer. The semiconductor wafer thus formed with the semiconductor devices are then divided into individual semiconductor chips by a dicing process that includes a sawing process conducted by a dicing saw.
In a such dicing process, it is commonly practiced to protect the semiconductor wafer, on which semiconductor devices are already formed, by an adhesive tape, such that the semiconductor devices are not damaged by the sawing process achieved by a dicing saw. The sawing may be conducted such that the depth of the dicing grooves, formed as a result of the action of the dicing saw, exceeds the thickness of the semiconductor wafer (full-cut dicing), or alternatively such that the depth of the dicing grooves is smaller than the wafer thickness (semi-full-cut dicing). Further, it is practiced to use an adhesive tape carrying a UV (ultraviolet)-cure type adhesive layer on a tape base for the foregoing adhesive tape, for facilitating the removal of the tape after the semiconductor wafer is divided into individual semiconductor chips. The tape base is typically formed of a polyvinyl chloride resin or a polyolefin resin.
After such a sawing process or alternatively during the sawing process, a cleaning process is conducted for removing dust particles formed as a result of the sawing, by applying a jet of a cleaning liquid such as water. Further, a first drying process is conducted immediately after the cleaning process for eliminating the cleaning liquid by applying an air jet.
In addition to the foregoing first drying process, it has been necessary, in the conventional dicing process, to conduct a second drying process, particularly in the case of the full-cut process, for removing water from the dicing grooves. In the dicing grooves, which are formed as a result of the sawing of the semiconductor wafer by the dicing saw, it should be noted that the adhesive layer on the tape base is exposed. This second drying process is conducted in view of the fact that the UV-curing of the adhesive layer tends to become imperfect when the UV-curing of the resin is conducted under a condition in which the adhesive layer is covered by a medium that contains oxygen such as water. Thus, it has been practiced in the conventional dicing process to carry out the second drying process in a dry N2 environment for at least 30 minutes.
Thus, when a six-inch semiconductor wafer is to be divided into semiconductor chips each having a size of 5 mmxc3x975 mm in the conventional dicing process, it takes about 5 minutes for sawing the semiconductor wafer into individual semiconductor chips, about 1 minute for the cleaning process as well as for the first drying process, about 30 minutes or more for the second drying process, about 1 minute for manually transporting the semiconductor chips from a dicing saw to an UV-curing apparatus together with the adhesive tape, and about 1 minute for curing the adhesive layer on the tape in the UV-curing apparatus. In addition, there may be an extra time needed for setting the semiconductor chips on the UV-curing apparatus in the state that the chips are held on the adhesive tape.
Thus, it will be understood that the conventional fabrication process of semiconductor devices has suffered from the problem of low throughput of production, primarily due to the existence of the second drying process in the dicing process. When the second drying process is eliminated, on the other hand, the adhesive tape remains sticky in correspondence to the part of the tape where the dicing grooves are formed, and the semiconductor chips may carry uncured, sticky adhesives thereon when the chips are picked up from the tape. When this occurs, the yield of production of the semiconductor device in the later process, such as the packaging process, may be deteriorated.
Accordingly, it is a general object of the present invention to provide a novel and useful method of fabricating a semiconductor device and an apparatus therefor wherein the problems described heretofore are successfully eliminated.
Another and more specific object of the present invention is to provide a fabrication process of a semiconductor device that can successfully reduce the time, and hence cost, needed for a dicing process for dividing a semiconductor wafer into individual semiconductor chips.
Another object of the present invention is to provide a method of improving the yield of production of semiconductor devices, by eliminating the damaging of semiconductor chips that may occur in a dicing process when transporting the semiconductor chips, divided from a common semiconductor wafer in the dicing process, from a sawing unit to a UV-curing unit in the state that the semiconductor chips are held on a flexible adhesive tape.
Another object of the present invention is to provide a method of fabricating a semiconductor device, comprising the steps of:
covering a surface of a semiconductor substrate by an adhesive tape carrying thereon an ultraviolet-curing type adhesive layer;
sawing said semiconductor substrate into individual semiconductor chips in a state that said semiconductor substrate is covered by said adhesive tape;
applying a dry gas to said adhesive tape in a state that said adhesive tape carries thereon said semiconductor chips;
applying an infrared radiation to said adhesive tape in a state that said adhesive tape carries thereon said semiconductor chips; and
curing said adhesive layer on said adhesive tape in a state that said adhesive tape carries thereon said semiconductor chips, by irradiating an ultraviolet radiation to said adhesive tape;
said step of applying said dry gas, said step of applying said infrared radiation and said step of curing said adhesive layer being conducted substantially simultaneously.
Another object of the present invention is to provide an apparatus for fabricating a semiconductor device, comprising:
an ultraviolet radiation source;
a lamp house body surrounding said ultraviolet radiation source, said lamp house body carrying a mirror surface;
an opening provided on said lamp house body, said opening being adapted for supporting semiconductor chips arranged on an adhesive tape;
an infrared radiation source provided in said lamp house body, such that said infrared radiation source is surrounded by said lamp house body; and
an air nozzle disposed such that said air nozzle applies a dry gas to said semiconductor substrate held on said opening.
According to the present invention, the drying process for eliminating water or moisture from the part of the adhesive tape corresponding to the dicing grooves is conducted substantially concurrently to the curing process of the ultraviolet-curing resin, and the throughput of production of the semiconductor devices is improved substantially. As the curing of the adhesive layer is thus conducted in a dry environment substantially free from water or moisture, the curing of the adhesive layer proceeds completely and the problem of decreased yield of the semiconductor device production, caused as a result of the partially cured adhesive layer sticking to the semiconductor chips, is successfully and effectively avoided. Further, as the sawing of the semiconductor substrate is conducted in the state that the semiconductor substrate is protected by the adhesive tape, mechanical damage to the semiconductor chips is minimized during the dicing process.
Another object of the present invention is to provide a method of fabricating a semiconductor device, comprising the steps of:
covering a surface of a semiconductor substrate by an adhesive tape carrying thereon an ultraviolet-curing type adhesive layer;
holding said semiconductor substrate on an opening of a lamp house including therein an ultraviolet radiation source, in a state that said semiconductor substrate is covered by said adhesive tape; and
sawing said semiconductor substrate into individual semiconductor chips in a state that said semiconductor substrate is held on said opening of said lamp house.
Another object of the present invention is to provide an apparatus for fabricating a semiconductor device, comprising:
an ultraviolet radiation source;
a lamp house body surrounding said ultraviolet radiation source, said lamp house body carrying a mirror surface;
an opening provided on said lamp house body; and
a vacuum chuck provided on said lamp house body so as to cover said opening, said vacuum chuck being adapted for supporting a semiconductor substrate thereon in a state that said semiconductor substrate is covered by said adhesive tape;
said vacuum chuck being formed of a material substantially transparent to an ultraviolet radiation produced by said ultraviolet radiation source.
According to the present invention, the dicing of the semiconductor substrate is carried out on the lamp house of the ultraviolet radiation source. Thereby, the process of transporting the diced semiconductor chips to the ultraviolet radiation source is no longer necessary, and the problem of the semiconductor chips being damaged during the transportation process due to the downward bulging of the tape, which in turn is caused by the gravity acting on the semiconductor chips, is successfully eliminated.
Other objects and further features of the present invention will become apparent when read in conduction with the attached drawings.